The present invention relates to a vehicle launching, and more particularly to an improved pneumatic system for launching aircraft.
One type of aircraft launcher known to the prior art utilizes pneumatic pressure to force a piston along a cylinder, the cylinder having an elongated slot extending longitudinally thereof to permit coupling of a launching shuttle external of the cylinder with the piston which is internal thereof. Problems have arisen in the effective operation of this type of aircraft launcher because the longitudinal slot, which is sealed behind the piston to maintain thrust pressure, creates a structural discontinuity in the cylinder thereby causing a loss of hoop strength, the characteristic ability of a closed cylinder to withstand radial forces. Without hoop strength, the slotted cylinder distorts upon the application of internal pressure, responding thereto like a curved beam which opens up along the sealed slot thereby venting the thrust pressure and adversely affecting launcher operation. Further problems have been experienced in stopping the fast-moving shuttle after launch within a relatively short braking distance without damaging the launching structure from the high-speed impact.
In aircraft launching systems known to the art, the problems associated with the structural discontinuity of the slotted launch cylinder have been treated by constructing the cylinder in as nearly a rigid fashion as possible. Thus, some cylinders have been embedded in concrete, while other cylinders are provided with structural support frames of a heavy nature so that the tendency of the cylinder to open up as a result of internal pressures is resisted by the structural strength of material external to the cylinder. Although such rigidly confined structures have been satisfactory in preventing distortion of the launch cylinder during operation, such cylinders, because of their unflexible nature, must be manufactured and aligned to very close tolerances with respect to the rest of the launching system in order to avoid high friction resistance to the piston which causes hot spots and undue wear. In addition, the heavy structural surroundings of such cylinders has resulted in aircraft launchers that are very difficult to handle and maneuver. Regarding the problems associated with braking the shuttle after launch, a variety of energy absorbing devices have been devised that stop the shuttle; however, these devices have not been entirely satisfactory in stopping the shuttle within a limited brake stroke without damaging the launching structure from the shock of high impact forces.